The present invention relates to a type of coasting device for a vehicle used to accomplish a relative rotating or free running between a driving wheel and a half shaft.
Undoubtedly, it is a much desired way for saving fuel to coast forward by inertia when a vehicle travels at a certain speed. However, automotive drive is generally a constant-engaging one at present. Therefore, when the rotation speed of the half shaft is lower than that of the drive wheel, not only is the coasting resistance of the vehicle increased, but also the engine is activated inversely to rotate idly with high speed, thus making the inertial energy of the vehicle unable to be utilized completely and ultimately increasing the wearing of operating parts.
The applicant filed an application for a patent for utility model entitled "A Coasting Device With Double Cone-Surfaces Clutch for Vehicle" on Sep. 22, 1992, in The People's Republic of China. The application resulted in the grant of a patent right on Jun. 26, 1993, (Patent No. ZL92220827.1) which patent is cited here as a reference.
The cited patent disclosed a type of coasting device with a clutch having double conical-shaped surfaces for a vehicle, which accomplished overrunning clutching by the coasting device, which device comprised a forward truncated cone-shaped surface for forward running and a second truncated cone-shaped surface for rearward running.
However, by further experimentation and research, it has been determined that the invention of the cited patent has certain defects. For example, the reacting speed of the device of the coasting device is slow and its internal and external gears, which are used as a locking device, are subject to such stress that they can be broken. While overrunning clutching, collisions between the conical surface for rearward running and its matched rear conicalshaped surface can occur since the double conical-shaped surfaces are formed as an integral part. This results in a disturbance in the coasting, which has a negative effect to the coasting, even to the extent that the vehicle may be unable to travel normally. Furthermore, it is a relatively complex structure.